Sand washing method and apparatus



Jan. 25, R954 R. R. BERG SAND WASHING METHOD AND APPARATUS Filed May 31, 1952 ic l.

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Patented Jan. 26, 1954 2,667,015 SAND WASHING METHOD AND APPARATUS Ralph E. Berg, Menlo Park, N. J., assignor to Mariblast Corporation,

poration of New Jersey Application May 31, 1952, Serial No. 290,906

Claims.

The present invention relates to a method and apparatus for cleaning the sides and hulls of ships and, more particularly, it relates to a sand washing method and apparatus whereby a mixture of fluidized sand and water is discharged against the sides and hulls of ships to remove sea growths and other loosely adhering deposits without effecting or removing paint from the ships.

In accordance with one sand washing method currently employed, water is fed under pressure through a tank containing sand. The water in its passage through the tank carries the sand with it to a discharge nozzle from which the mixture is played against the sides of a ship.

In another conventional method, a stream of high pressure air is passed to the top of a sealed tank containing water and sand. The water and sand are forced out of the bottom of the tank by the air and led to and admixed with a further stream of rapidly moving air. This final mixture of air, water and sand is then sprayed from a discharge nozzle against the side of a ship.

Other sand washing methods are also known and used but these methods may be considered as only incorporating refinements of the two above described processes.

Unfortunately, both of these above described methods are not entirely suitable because the wet sand in the tank and various discharge conduits and orifices has a tendency to clot or clump so that there is continual intermittent and sporadic plugging of the outlet passages and discharge line. As the result of this plugging, the stream of abrasive issues from the discharge nozzle with a slugging manner. In other words. as the clumps of sand block the various discharge conduits and orifices, there is a momentary drop in pressure at the mouth of the discharge nozzle. Then as the pressure builds up in the system, the clump of sand will be suddenly ejected outwardly with attendant vibration and pressure shock.

Thus the sand will not be evenly and uniformly distributed throughout the abrading stream. With such uneven distribution, the stream will not have a constant cleaning efiect.

The continual vibrations and pressure shock created by the continual jamming and clearing serve to fatigue the operator handling the discharge nozzle. Moreover, the discharge nozzle will have a tendency to jump out of the hands of the operator because of the slugging defect so that more care and effort is required on his part. This, too, is tiring.

It is the object of thevpresent invention to overcome and eliminate these difiiculties by providing a method and apparatus. for cleaning the sides of ships by washing the ships with a high Jersey City, N. J., a corpressure stream of water containing sand in an evenly distributed or fluidized state.

It is still another object of the present invention to provide a method. and apparatus whereby water under pressure may be forced upwardly into a bed of sand to render the sand fluid.

It is still a further object of the present invention to provide a sand washing method and apparatus for cleaning the sides of ships wherein a continual and even flow of water containing uniformly distributed sand throughout may be ejected against the sides of a ship.

It is yet another object of the present invention to provide a sand washing method and apparatus for cleaning the sides of ships wherein a stream of water and fluidized sand will be ejected against the sides of a ship and wherein said stream will contain a corrosion inhibitor.

One advantage of the present invention is that packing and clotting of sand in the storage tank outlets, discharge passages, and discharge nozzle is eliminated.

A still further advantage of the present invention resides in the fact that the use of an abrading stream containing fluidized sand will prevent any slugging effect and will provide a smooth continuous discharge.

Another advantage of the present invention is the fact that the operator handling the discharge nozzle will not be easily tired due to the absence of pressure and shock waves, which would otherwise result if the system were to jam.

An additional advantage of the present in vention is the fact that the amount of sand in the stream may be varied within fairly large limits since the sand is in a fluid state and will not block the system despite its concentration.

Moreover, the present invention has the advantage that the abrading stream will at all times deliver with a constant uniform cleaning efiect.

Other objects and advantages of the present invention will become more apparent as it is described in-detail below, with particular reference to theaccompanying drawings, wherein Fig. l is a side View in partial section showing the apparatus employed in the present invention. and

Fig. 2 is a plan view of the apparatus shown in Fig. 1.

Briefly describing the present invention, a stream of water is forced upwardly under pressure into the bottom of a tank having a perforated plate disposed therewithin. The perforated plate is located just above the bottom of the tank and is adapted to hold a bed of sand. The entire tank is closed to atmospheric pressure at all times during the operation of the system. As thef'water passes into the tank, it is uniformly distributed to the bed of sand by atmospheric pressure.

virtue of the perforated plate. The upwardly rushing water expands the bed of sand and causes the sand particles to take on a continual motion. The bed of sand thus acts as a fluid layer and exhibits flow characteristics typical of a fluid.

The water in the tank will be divided into two layers. The bottom layer, shown as B in Fig. 1, will contain water and fluidized sand, and the top layer, shown as A in Fig. 1, will contain clear water. Due to gravity, the fluidized sand will be found only in the lower portion of the tank.

The fluidized sand and water then pass through an outlet conduit extending from the perforated plate to a discharge line. The clear water in the top layer will pass into an overflow line which joins the stream of fluidized sand and water going from the tank to the discharge line. The final stream of water and sand is then led to a rubber hose having a discharge nozzle.

With particular reference to Fig. 1, there is shown a tank H having a downwardly rounded bottom portion l2 and a downwardly rounded top portion 53. This tank Ii sealed to the A plate i4 is disposed within and across the tank just above the bottom portion i2. This plate M has a plurality of perforations 14a therein so that water may pass upwardly through the plate.

An outlet l5 disposed in the bottom of the tank H, is connected to an inlet pipe l6, which inlet pipe is adapted to carry a stream of high pressure water. Extending downwardly from the plate i4 and through the bottom portion I2 is a discharge pipe I! which leads to and joins a Venturi conduit l8. The open top of pipe i1 is higher in level than the inlet I5. The conduit 48 is connected to a rubber hose l9 having a discharge nozzle 20.

Connected to the side of the tank H and near the top thereof is an outlet pipe -2 l which extends down along the tank and then joins the conduit 18. The amount of sand and water flowing in the discharge pipe l! and eventually joining the water from the outlet pipe 2! may be regulated through the valve Ha. Thus by manipulation of valve Ha, the abrading strength of the discharge stream can be controlled. In other words, it is possibleto regulate the amount of abradant in the discharge stream. Also disposed-at the side of the tank l l and at a point above the plate 1-4 is a still further inlet pipe 22 through which a suitable corrosion inhibitor may be added to the sand and water mixture.

It is to be noted that the top portion of the tank H has a plug 23 which may be removed so that sand may be placed in the tank. The top portion [3 is downwardly rounded so that when sand is shoveled or thrown onto this portion, the sand will slide downwardly and through the opening 24.

In operating the apparatus described above, the plug 23 is removed from the to portion 13 and sand is then shoveled through the hole 24. This sand will fall down into the tank H and come to rest on the perforated plate I l. The amount of sand placed in the tank should be slightly more than one-half of the volume between the top of the tank H and the plate it. It is true that some of the dry sand will pa s through the perforations Hid but this amount of Sand is negligible. Moreover, when the apparatus is started up and water is in the tank ii, the sand which has fallen through the perforations [4a will be carried for the most part up into zone B.

The plug 23 is then replaced in the tank H so that the tank is sealed to atmospheric pressure. A. stream of water, at approximately p. s. i. g., is then passed through pipe 16 to the bottom portion of the tank l l and then upwardly into the bed of sand. The water, which is uniformly distributed to the sand by means of the perforated plate it, expands the bed of sand 15 to 20 percent and causes the bed of sand to become fluid, asshown at zone B. The fluid sand and water in zone B will then escape downwardly through pipe I! to the conduit l8 and finally out through the rubber hose l9 and discharge nozzle 26. The clear water in zone A will pass out through the over-flow pipe 21 and then join the fluidized sand and water coming from pipe H.

of course, it is clear that the supply of sand in the tank will eventually be exhausted, at which time it becomes necessary to shut down the apparatus and refill the tank with sand.

If it is desired to prevent rusting of the side of the ship being cleaned, a corrosion inhibiting liquid such as a dilute phosphoric acid solution or a dilute chromate salt solution may be admitted to the tank through pipe 22. The corrosion inhibiting liquid may be applied to the bed of sand before the water is admitted to the tank or it may be supplied continuously to the tank during operation.

Although I have described water as the conveying medium in my invention, it is also quite possible to employ high pressure air in place thereof. In this case, air at 100 p. s. i. g. is passed through pipe 16 to the tank H. The upwardly rushing air will expand and fluidize the bed of sand in the same manner as if water were used. The air in the tank will divide into two zones. The top zone A will contain air only and the bottom zone B will contain air and fluidized sand. The fluidized sand and air from zone B will then pass downwardly through the pipe I"! to the various conduits until it is discharged at nozzle 20. The clear air in zone A will pass out through pipe 2! and join the mixture of fluidized sand and air at Venturi conduit it.

Although the invention has been described for the particular use of cleaning ships, it is to be understood that the same apparatus and process may be used for polishing, buifing and honing of various other surfaces by employing a very fine light abrasive.

Moreover, by using extremely high fluid pressures from 1000 to5000 p. s. i. g., a powerful cutting action may be obtained without the generation of excessive heat.

While the invention has been described in detail and shown with respect tothe accompanying drawings, it is not to be limited to such details, since many changes and modifications may be made in the invention without departing from the spirit and scope thereof. Hence, it is desired to cover any and all forms and modifications of the invention which may come within the language and scope of any one or more of the appended claims.

I claim:

1. Apparatus for feeding a fluid abrading mixture to a discharge conduit, said apparatus comprising a tank having a rounded bottom portion, a perforated plate within said tank and disposed above said bottom portion, said plate adapted to hold an abrasive thereon, said tank being closed to atmospheric pressure, an inlet in said bottom portion for admitting a fluid under pressure, an outlet pipe extending from said plate through said bottom portion to a discharge conduit, an over-flow pipe disposed above said plate and joining said discharge conduit.

2. Apparatus for feeding a fluid mixture of said to a discharge conduit, said apparatus comprising a tank having a perforated plate disposed above its bottom portion and being closed to atmospheric pressure, said plate adapted to support a bed of sand, an inlet in the bottom of said tank whereby a fluid may be admitted to said tank under pressure, an outlet pipe extending from said plate through the bottom of said tank to a discharge conduit, an overflow pipe disposed above said plate and joining said discharge conduit.

3. In a sand washing apparatus, a tank having a perforated plate disposed therewithin and above its bottom portion, said tank being closed to the atmosphere, said plate adapted to support a bed of sand, an inlet conduit for admitting fluid under pressure to the bottom of said tank at a point below the plate, an outlet pipe above said conduit, and an overflow pipe disposed above said plate, said outlet and overflow pipes both leading to a common discharge conduit.

4. In a sand washing apparatus for cleaning the sides and hulls of ships, a tank adapted to receive sand and fluid, a plate disposed within said tank and having a plurality of perforations therein, said plate adapted to support a bed of sand thereon, an inlet pipe at the bottom of said tank and adapted to carry a stream of high pressure fluid up through said bed of sand, an outlet pipe within said tank extending from said plate down through the bottom of said tank and joining a discharge conduit, and an overflow pipe sure fluid, a perforated element dividing said tank into an inlet chamber and a sand retaining chamber disposed one above the other and within the latter of which a bed of sand is adapted to be supported by said perforated element, an inlet pipe leading to said inlet chamber and adapted to carry a stream of pressure fluid into said inlet chamber, from which it is directed upwardly through said perforated element into said bed of sand whereby said sand is fluidized, an outlet pipe leading from the lower ing said discharge conduit.

6. In an apparatus for sand washing a surface, a tank adapted to receive a bed of sand in the lower portion of said tank, pressure fluid delivery the vicinity of the lower portion a discharge conduit communicating with said and joining said discharge conduit.

7. That method of sand washing a surface lecting the fluidizing medium pursuant to its having moved through said sand, delivering such collected fluidizing medium toward the surface to be sand washed while confining such fluidizing medium to a definite path of travel, and introducing the fluidized sand into said path of travel So that such sand may be conveyed toward and forciby directed against said surface under the action of said fluidizing medium as it traverses said path.

8. That method of sand Washing a surface which resides in forcing a, fluidizing medium through a quantity of sand in order to fluidize the same, maintaining said sand substantially within the limits of a definite zone While it is being fluidized, collecting the fluidizing medium Within another definite zone is being fluidized,

sand from a point located at a below the second-mentioned zone into said path RALPH R. BERG. References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 554,299 Parker Feb. 11, 1896 1,054,775 I-Iull Mar. 4, 1913 2,042,120 Palmiter May 26, 1936 2,317,837 Webster Apr. 27, 1943 2,372,957 Keefer Apr. 3, 1945 

